The radical cations of a series of bridged bicyclo[5.1.0]octa-2,5-dienes have been generated by photoinduced electron transfer to strong electron acceptors (chloranil, fluoranil) in solution. Chemically induced dynamic nuclear polarization effects observed during the reactions of simple bridged systems (1b-d,j) indicate that the intermediates are bis-homoaromatic (BHA) systems of B2 symmetry. These are the first homoaromatic radical cations of any structure type. Introduction of substituted exo-methylene groups as bridging units (1e-i) leads to a composite structure type with contributions from bis-homoaromatic structures of A2 and B2 symmetry and/or from a vinylcyclopropane structure (VCP) with an antisymmetric singly occupied molecular orbital.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry